Panel Heaters

ABSTRACT

A panel heater with enhanced safety features for us as room heaters disposable on at least one of a wall and a floor includes: a flat panel heater component; at least one protrusion provided on at least one of a top surface and a bottom surface of the flat panel heater component; and a covering surrounding at least one of the top surface and the bottom surface of the flat panel heater component. The flat panel heater component includes one of a) an electrical heating element incorporated in an oil filled chamber; and b) a wire heating element covered with an electrical insulating material. The at least one protrusion creates an air gap between at least one of the top surface and the bottom surface of the flat panel heater component and the covering, thereby reducing temperatures attained on surfaces of the flat panel heater component and the covering significantly.

FIELD OF INVENTION

The invention relates to panel heaters. More particularly, the invention relates to a panel heater with enhanced safety means.

BACKGROUND OF INVENTION

U.S. Pat. No. 4,728,780 discloses panel heaters which are used as room heaters, disposed on walls, ceiling or floors. The panel heater is incorporated with a heating pipe, an electric heating wire running through it and aluminum granules stuffed between the two. Because spherical aluminum granules are closely packed, the heat conductivity of such panel heater is very good, which minimizes the heat loss and reduces the time to heat up a room. An automatic on-off switch is generally provided to control room temperature.

-   -   ) There also panel heaters used as room heaters disposed on wall         ceiling or floor. These heaters have electrical heating element         incorporated in oil which heats up the panel and the panel         radiates heat into surrounding medium. In a variation electrical         heating element embedded in resinous electrical insulants that         are thermally conducive and embedded in between covered metal or         non-metallic panels facing sheets are also made.     -   Such panel heaters when used at heights less than 6′ ft from         floor level are provided with safety precautions not to cover         the panels as this can elevate temperatures and result in fire         hazards. The statutory instructions for example, IEC 60335-2,         and UL 2021 respectively stipulates that when the heater is         covered with 25-mm felt, the temperature of such coverings         should not exceed 150 deg centigrade, and that when covered with         specified materials they should not get ignited glow or emit         embers.     -   2) While the experiment deals with specified materials there is         always possibility of more non-conductive materials used as         covering such as higher thickness material or much lower thermal         conductive material that can far exceed the limit temperature         and present a possible fire hazard.

OBJECT OF THE INVENTION

It is therefore an object of the invention to propose a panel heater which can maintain higher safety standard and will not raise temperatures and simultaneously maintain the stipulated requirement of the statutory standards even for coverings of lower conductivity thermal.

SUMMARY OF THE INVENTION

Accordingly there is provided an improved panel heater in which each of the top front faces and the bottom front faces of the panel, are provided with at least one protrusion extending between 6 mm to 25 mm by maintaining higher thickness at the protrude portion. Width of the protrusions can be selected as is convenient. Protrusions can be integrally, configured during manufacturing of the panel covering, or could be provided with separate protrusion fixed to panel covering subsequently. The protrusion members can either be configured as a continuous member or can be provided at specific intervals across the length of the top and bottom edge of the panel.

The protrusion members can be shaped to add to presentable look of the heater. Further projection at the center of the panel can be added depending on size of panel.

Such a construction ensures creation of an air gap between the panel's surface and the covering material, (1) This not only avoids direct contact but will also provide some heat transfer due to air gap during test for a possible abnormal or erroneous operating. (The gap thus can be fixed relation to surface temperature of panels and allowed raise of temperature of any covering). By adjusting the dimension of the air gap, the temperature of the covering material can be controlled.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1( a) Shows a prior art single-wall mounting panel heater.

FIG. 1( b) Shows a single-wall mounted panel heater according to the Invention.

FIG. 1( c) Shows a panel heater with protrusions according to the invention.

FIG. 1( d) Shows both sides of a panel heater according to the present invention.

DETAIL DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

As shown in FIG. 1( a), a panel heater (B) according to prior art is mounted on a wall (A) via its mounting legs (E). When the heater is covered with material such as felt (C). The covering (C) touches the panel (B), thereby reaching instantaneously with switching on of the heater nearer to the surface temperature of the panel (B).

Heat removed from a panel per unit area is dependant on thermal conductivity and thickness of the covering for 1 deg centigrade temp difference. Hence temperature of the panel increases to maintain required difference of temperature to transfer all the heat generated through the covered material.

FIG. 1 (b) shows the effect of protrusion members (D) provided at bottom and top according to the invention, which creates air gap between the panel surface (B) and the covering material (C) and the panel (B).

In case, the panel (B) is reachable on either side and can be subjected to such abnormal operation, the edge projection (D) should be used on both sides of the panel (B) as shown in FIG. 1( d).

This invention is applicable for all panel heaters whether fixed or movable and electrical or oil filled of any material and where a possibility exists for abnormal operation by covering the heater.

For data of typical experiment shows distinctive advantage of this improved construction with protrusions of 15 mm and 20 mm. The panel is covered by felt 50% thicker than 25 mm specified in test standard to demonstrate its effectiveness.

Typical panel Test Data

600×600 mm nominal size

Rating 420 watts.

(Covering is 50% thicker than standard felt covering of 25 mm as required by test standards)

Temperature Temperature Temperature when when covered when covered covered with felt with felt with felt. Location of temp Flat panel without Panel with 15 mm Panel with 20 measurement protrusion protrusion mm protrusion Temperature of Average 180 deg Average 138 deg Average 130 Panel surface centigrade test centigrade deg centigrade abandoned Temperature Average 165 deg Average 110 deg Average 90 deg covering felt on centigrade - test centigrade centigrade face towards abandoned panel ** There is thus significant reduction in temperature measured on cloth when it is covered on panel with 15 and 20 mm protrusion.

For any panel depending on wattage for unit area, level of safety increases with increased gap up to certain measure after which the improvement benefit may not be significant.

By using described panels of this invention safety can be greatly enhanced against fire hazard, when the surface is covered for any reason where no temperature limit or cut off control is used and also where such device fails. 

1-7. (canceled)
 8. A panel heater with enhanced safety features for us as room heaters disposable on at least one of a wall and a floor, the panel heater comprising: a flat panel heater component comprising: one of a) an electrical heating element incorporated in an oil filled chamber accommodated within a flat covering panel and supplied with electrical energy from a conventional source; and b) a wire heating element covered with an electrical insulating material accommodated within a flat covering panel and supplied with electrical energy from a conventional source; at least one protrusion provided on at least one of a top surface and a bottom surface of the flat panel heater component; and a covering surrounding at least one of the top surface and the bottom surface of the flat panel heater component, wherein the at least one protrusion creates an air gap between at least one of the top surface and the bottom surface of the flat panel heater component and the covering, thereby reducing temperatures attained on surfaces of the flat panel heater component and the covering significantly.
 9. The panel heater as claimed in claim 8, wherein the at least one protrusion extends from at least one of the top surface and the bottom surface of the flat panel heater component by about 6 mm to about 25 mm.
 10. The panel heater as claimed in claim 8, wherein a thickness of the at least one protrusion is selected to correspond to an expected temperature rise on a surface of the flat panel component.
 11. The panel heater as claimed in claim 8, wherein the at least one protrusion is configured to be integrated with at least one of the top surface and the bottom surface of the flat panel heater component during manufacture or before usage.
 12. The panel heater as claimed in claim 8, wherein the at least one protrusion is configured as an independent member configured to be undetachably attached to at least one of the top surface and the bottom surface of the flat panel heater component.
 13. The panel heater as claimed in claim 8, wherein the shape of the at least one protrusion is selected from the group consisting of rectangular, square, and trapezoidal. 